LEG Example Backend
===================

This is a simple example LLVM backend for an ARM-like architecture: 'LEG'.

Check out the slides from the tutorial given at Euro LLVM Developers' Conference 2014, Edinburgh:
    http://llvm.org/devmtg/2014-04/PDFs/Talks/Building%20an%20LLVM%20backend.pdf

Look out for us at the USA LLVM Developers' Conference, October 28-29, San Jose:
    http://llvm.org/devmtg/2014-10/


Fraser Cormack & Pierre-André Saulais, Codeplay Software

Getting Started
===============

The LEG repositories (llvm-leg, clang-leg) both track tip, and aren't tied to any specific revision of LLVM/Clang.

Tried & tested build systems:
*  CMake
Tried & tested compilers:
*  gcc 4.9.1
*  clang 3.5

Building with in-tree clang (optional)
--------------------------------------

    cd llvm-leg
    git clone [email protected]:codeplaysoftware/clang-leg.git tools/clang

Building with make
------------------

    cd llvm-leg
    mkdir build && cd build
    cmake -G "Unix Makefiles" -DCMAKE_BUILD_TYPE:STRING=DEBUG(/RELEASE) -DLLVM_TARGETS_TO_BUILD:STRING=LEG(,X86,...) ../
    make -j9

Building with ninja
-------------------

    cd llvm-leg
    mkdir build && cd build
    cmake -G "Ninja" -DCMAKE_BUILD_TYPE:STRING=DEBUG(/RELEASE) -DLLVM_TARGETS_TO_BUILD:STRING=LEG(,X86,...) ../
    ninja


Compiling some code
-------------------

    cd llvm-leg

    ### Compile IR -> Assembly ###
    ./build/bin/llc -march leg -o ex1.s docs/Codeplay/examples/ex1.ll
    cat ex1.s

    ### Compile IR -> ELF Object File ###
    ./build/bin/llc -march leg -filetype=obj -o ex1.o docs/Codeplay/examples/ex1.ll
    xxd ex1.o

    ### Compile Source -> Assembly with in-tree clang (via clang-leg) ###
    ./build/bin/clang -cc1 -triple leg-unknown-unknown -S -o ex1.s docs/Codeplay/example/ex1.c
    cat ex1.s

    ### Compile Source -> Assembly with in-tree clang (via clang-leg) ###
    ./build/bin/clang -cc1 -triple leg-unknown-unknown -o ex1.o docs/Codeplay/example/ex1.c
    xxd ex1.0

Low Level Virtual Machine (LLVM)
================================

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a toolkit for the construction of highly optimized compilers,
optimizers, and runtime environments.

LLVM is open source software. You may freely distribute it under the terms of
the license agreement found in LICENSE.txt.

Please see the documentation provided in docs/ for further
assistance with LLVM, and in particular docs/GettingStarted.rst for getting
started with LLVM and docs/README.txt for an overview of LLVM's
documentation setup.

If you're writing a package for LLVM, see docs/Packaging.rst for our
suggestions.